Green Line trolleys collide at Boylston Street Station

Video from inside a Massachusetts Bay Transportation Authority station where two Green Line trains collided shows a passenger being tossed to the ground upon impact of the trolleys.

The MBTA released the video one day after the trains collided at the Boylston Street Station shortly before noon on Thursday, injuring 37 people.

Officials have concluded that no cellphone use or mechanical failures have been found in the early investigation into the cause of the collision.

"People went flying, got their knees banged up. It was pretty hectic," one rider said.

Chief of Boston EMS James Hooley said there were no serious injuries.

"Several of them complained of neck and back pain that required them to be carried up and extracted. But the majority of them -- 28 or so -- were walking, wounded," Hooley said.

At the time of the crash, there were about 200 people on the trolleys. The operator of the second trolley was among the injured.

MBTA officials said it was a "slow-speed crash" and no trolleys were damaged.

Both trolley operators have been tested for drug and alcohol use, which is standard procedure for any crash involving an MBTA vehicle.

MBTA spokesperson Joe Pesaturo said Saturday that one of the trolley operators was cited in July 2009 for going 13 mph over the speed limit. The operator, who hasn't been named, was disciplined and retrained, according to Pesaturo.